Muffler for internal combustion engines



K. F. NOWAK March 22, 1960 MUFFLER FOR INTERNAL COMBUSTION ENGINES Filed June 30, 1958 Pee 2,929,462 MUFFLER FOR INT RNAL COMBUSTION ENGINES KlausFrederick Nowak, Torontii, Ontario, Canada imiiic'aaaa june 30, nss, steam-145303 6 Claims. (21. 181 42} This invention relates to a muffler for internal combustion engines.

The objects of the invention, generally, are to provide an improved mufiler for internal combustion engines, improved in that it creates less back pressure than known mufilers at any given orifice at the same time it reduces the exhaust noise considerably, is inexpensive to manufacture and can be easily installed and removed.

A specific object of the invention is to provide a mufiler wherein the fumes-discharging duct is formed with a portion of abruptly-decreasing diameter, followed (preferably immediately) by a gradually-diverging portion, better to attenuate or reduce noise.

Another specific object of the invention is to provide a mufiler wherein sound-absorbing fibrous material is interposed between an inner fumes-discharging duct and an outer spaced shell, the inner duct having perforations to expose the sound-absorbing material.

Another specific object of the invention is to provide a muffler made of two telescoped shells which interlock in operative assembled position, without the use of rivets, soldering, welding or other similar means, but which can be disassembled easily when required; the inner shell being formed to define with the outer shell when so assembled, a space in which is received a sleeve of sound-absorbing material of desired thickness.

Other objects and advantages of a muffier made in accordance with the invention may be gleaned by reading the specification to follow in the light of the drawing.

In the drawing,

Figure 1 is a part-sectional, part-elevation view of one form of the device;

Figure 2 is an end view, as seen from right to left in Figure 1; and

Figure 3 is a fragmentary view of a modified form.

Referring now by numerals to the drawing, the mufiler M, is adapted to be operatively connected to the rear end of the tail pipe P leading from the exhaust manifold (not shown). The muffler may be clamped to (or into) the tail pipe in an approved manner.

In the form shown in Figures 1 and 2, the mufiier comprises an outer shell 10, an inner shell 11, and a sleeve of suitable noise-absorbing material 12 disposed between co-facing portions of the shells.

The outer shell is formed with a forward portion 14 of uniform diameter, and a rear portion 15 of gradually-increasing diameter, the rear end of the portion 15 being formed with an inwardly curved flange or rim 16. In the finished muffier, and as will be explained later, the forward end of the outer shell is preferably formed with pressed-out protuburances 17 located close to the forward end of the shell.

The inner shell 11 is formed with a forward portion 18 of uniform diameter slightly less than the inside diameter of the outer shell 10, followed by a relatively-narrow portion 19 of decreasing diameter to define a throat 20, and then followed by a rear portion 23 of gradually-increasing diameter. The rear end of the inner shell is preferably 2 formed with an outwardly-curved portion forming a lip 33 adapted to engage the inwardly-curved rim 16 of the outer shellwhen both shells are in operative assembled relationship,gas shown in Figure 1. The two shells are in such assembled relationship when the forward edge of the inner shell bears against the protuburances 17.

More easily to assemble the inner and outer shells, as by slipping theinner shell from left to right, as seen in Figure 1; into the outer shell, the inner shell is slit longitudinally from its rear end, at least partially, toward the forward end.

Within the annular space defined between the inner and outer shells is inserted some suitable noise-absorbing material as aforesaid.

To render the material effective, the inner shell is formed with a number of apertures 21.

If desired, the noise-absorbing material may be preformed as a sleeve, slit lengthwise so that it can be inserted over the inner shell from right to left as seen in Figure l.

The mufiler is easily assembled from its three component parts. The inner shell with sleeve of noise-absorbing material is inserted into the outer shell from left to right, the inner shell being slightly deformed so that it will pass freely through the rear end of the outer shell, until the flange 33 clears the rim 16; then the inner shell is pushed slightly rearwardly to bring the flange 33 in engagement with the inside of the rim 16, and the metal of the outer sleeve pressed in to form the protuburances 17.

In the form shown in Figure 3, the outer shell is formed with a rear portion 15A parallel with the forward portion 14A but of increased diameter. The rear end of the portion 23A of the inner sleeve or shell 11A is formed with a lip or rim 33A adapted to engage with the inner face of the portion 15A when both shells are assembled into the mufiler. The inner and outer shells are so held in engagement, as aforesaid, by a rim 16A fitting over the outer shell and under the lip 33A. The rim 16A may be held to the outer shell by any suitable means.

The form shown in Figures 1 and 2 is intended particularly for fast moving vehicles. In trucks and tractors, the form shown in Figure 3 may be used satisfactorily.

What I claim is:

l. A mufiler comprising: telescoped inner and outer shells, said inner shell having, a straight portion adapted at its forward end to be operatively attached to an exhaust pipe from an internal combustion engine, a restricted portion forming a throat rearwardly of said straight portion, and an apertured outwardly-tapered portion rearwardly of said restricted portion; said outer shell having, a straight portion telescoped on the straight portion of said first shell and a portion rearwardly of its straight portion and spaced from said inner shell to provide an annular space; and a sleeve of noise-absorbing material substantially filling the annular space.

2. A mufiier comprising: telescoped inner and outer shells, said inner shell having, a straight portion adapted at its forward end to fit on an exhaust pipe from an in ternal combustion engine, a restricted portion forming a throat immediately rearwardly of said straight portion, and an apertured outwardly-tapered portion immediately rearwardly of said restricted portion; said outer shell having, a straight portion telescoped on the straight portion of said first shell and an outwardly-tapered portion immediately rearwardly of its straight portion and substantially parallel with the rear portion of said inner shell to provide an annular space; and a sleeve of noise-absorbing material substantially filling the annular space.

3. In a mufiler as in claim 1, said outer shell being formed with a downwardly-turned rim on its rearward end, engaged by the rear end of said inner shell and determining the rearward displacement of said inner shell within said outer shell.

4. In a muffler as in claim 1, said outer shell being formed with a downwardly-turned rim on its rearward end and formed with inwardly-extending protuburances 7 adjacent to the forward end, and said inner shell engaging 'and said inner shell being formed with an outwardlycuwed lip engaging said rim to determine rearwardly displacement of said inner tube within said outer shell.

6. In a mufiler as in claim 1, said outer shell being formed with a curved rim on the rear end and formed aeaama V 4 with inwardly-extending protuburances adjacent its forward end, and said inner shell being formed with an outwardly-curved lip on its rear end engaging said rim and having its forward end closely adjacent said protuburances so that said inner shell may be retained in assembled operative position within said outer shell.

References Cited in the file of this patent UNITED STATES PATENTS 1,941,222 Pew et a1 Dec. 26, 1933 1,995,071 Mackenzie et al Mar. 19, 1935 2,342,905 Smellie Feb. 29, 1944 2,485,392 Leadbetter Oct. 18, 1949 2,613,758 Cullum Oct. 14, 1952 FOREIGN PATENTS 7 France Apr. 25, 1951 

